Removed a mutable default param in Serializer.serialize().

I haven't seen this pop up explicitly as a bug in code; only noticed it
through code inspection.
Update cookbook.rst

I think the 'alternative approach' is in the wrong place
import slugify from django.utils.text
Merge pull request #1110 from gutworth/patch-1

import slugify from django.utils.text
Fixing base class reference
Fixing base class reference
Merge pull request #1111 from eamonnfaherty/master

Fixed base class reference and changed attribute name
Added section about httpie

tastypie plus httpie make up a very nice combination for interacting with RESTful web services.
Merge pull request #1117 from nikos/patch-1

Added section about httpie
import unquote within try/except block to support both python 2&3
Merge pull request #1120 from copelco/gis-python3

Add Python 3 support in contrib.gis
Fixed biplist URL
Merge pull request #1121 from qrilka/patch-1

Fixed biplist URL
Merge pull request #1108 from steffann/patch-1

Update cookbook.rst
Adding chrome browser tool

Adding Postman to list of chrome browser tools
Fixed a typo in index.rst.

Changed "an" to "a" at line 4.
Replacing "it's" with "its" in two places.

Brief visit from the apostrophe police, carry on.
Merge pull request #1130 from sanketsaurav/patch-1

Fixed a typo in index.rst.
Merge pull request #1131 from erictheise/patch-1

Replacing "it's" with "its" in two places.
Merge pull request #286 from malcolmt/mutable-default-fix

Removed a mutable default param in Serializer.serialize().